1. Technical Field
The present invention relates to a lens, especially for modifying light beam of a LED configured on a bottom recess of the lens.
2. Description of Related Art
FIG. 1 is a prior art.
U.S. Pat. No. 7,254,309 discloses a lens for a LED, the light emitted from the LED chip 40 enters the lens 20 through the incident surface 22. A portion of the light is reflected by the reflective surface 23 to the second refractive surface 32 in an internal total reflection manner, and then the light is refracted by the second refractive surface 32 and emits out of the second refractive surface 32 of the lens 20 along a lateral direction of the lens 20, such as a first optical path P1 of the lens 20. The other portion of the light enters the lens 20 through the incident surface 22 and then directly emits out of the lens 20 to toward the lateral directions of the lens 20 respectively to be refracted by the first refractive surface 31 along a second optical path P2 and the third refractive surface 33 along a third optical path P3. The first optical path P1, the second optical path P2 and the third optical path P3 are in a direction substantially normal to the central optic axis C of the lens 20. Hence the light emitted from the LED chip 40 is directed towards a lateral direction of the lens 20.
After the light emitted from the LED chip 40 enters the lens 20, the intensity distribution of energy of the emitted light can be divided in a zone 1, a zone 2 and a zone 3. The zone 1 is located between the central optic axis C and the connection line of the first cross point c1 to the second cross point c2. The zone 2 is located between the connection line of the first cross point c1 to the fourth cross point c4 and the zone 1 (the third cross point c3 is located on the connection line of the first cross point c1 to the fourth cross point c4). The zone 3 is located between the zone 2 and the bottom surface 21. The energy distribution is strongest in the zone 1, then sub-strong in the zone 2, and weakest in the zone 3.